Merge branch 'ua/os-version-capability' into jch

The value of "uname -s" is by default sent over the wire as a new
capability, with an opt-out for privacy-concious folks.

* ua/os-version-capability:
  version: introduce osversion.command config for os-version output
  connect: advertise OS version
  t5701: add setup test to remove side-effect dependency
  version: extend get_uname_info() to hide system details
  version: refactor get_uname_info()
  version: refactor redact_non_printables()

Author: gitster

Documentation/config/transfer.adoc

@@ -125,3 +125,19 @@ transfer.bundleURI::
 transfer.advertiseObjectInfo::
 	When `true`, the `object-info` capability is advertised by
 	servers. Defaults to false.
+
+transfer.advertiseOSVersion::
+	When `true`, the `os-version` capability is advertised by clients and
+	servers. It makes clients and servers send to each other a string
+	representing the operating system name, like "Linux" or "Windows".
+	This string is retrieved from the `sysname` field of the struct returned
+	by the uname(2) system call. If the `osVersion.command` is set, the
+	output of the command specified will be the string exchanged by the clients
+	and the servers. Defaults to true.
+
+osVersion.command::
+	If this variable is set, the specified command will be run and the output
+	will be used as the value `X` for `os-version` capability (in the form
+	`os-version=X`). `osVersion.command` is only used if `transfer.advertiseOSVersion`
+	is true. Refer to the linkgit:git-config[1] documentation to learn more about
+	`transfer.advertiseOSVersion` config option.

Documentation/gitprotocol-v2.adoc

@@ -190,6 +190,23 @@ printable ASCII characters except space (i.e., the byte range 32 < x <
 and debugging purposes, and MUST NOT be used to programmatically assume
 the presence or absence of particular features.
 
+os-version
+~~~~~~~~~~
+
+In the same way as the `agent` capability above, the server can advertise
+the `os-version` capability to notify the client the kind of operating system
+it is running on. The client may optionally send its own `os-version` capability,
+to notify the server the kind of operating system it is also running on in its
+request to the server (but it MUST NOT do so if the server did not advertise the
+os-version capability). The value of this capability may consist of ASCII printable
+characters(from 33 to 126 inclusive) and are typically made from the result of
+`uname -s`(OS name e.g Linux). If the `osVersion.command` is set, the value of this
+capability are made from the ouput of the command specified. The os-version capability
+can be disabled entirely by setting the `transfer.advertiseOSVersion` config option
+to `false`. The `os-version` strings are purely informative for statistics and
+debugging purposes, and MUST NOT be used to programmatically assume the presence or
+absence of particular features.
+
 ls-refs
 ~~~~~~~
 

builtin/bugreport.c

@@ -12,10 +12,10 @@
 #include "diagnose.h"
 #include "object-file.h"
 #include "setup.h"
+#include "version.h"
 
 static void get_system_info(struct strbuf *sys_info)
 {
-	struct utsname uname_info;
 	char *shell = NULL;
 
 	/* get git version from native cmd */
@@ -24,16 +24,7 @@ static void get_system_info(struct strbuf *sys_info)
 
 	/* system call for other version info */
 	strbuf_addstr(sys_info, "uname: ");
-	if (uname(&uname_info))
-		strbuf_addf(sys_info, _("uname() failed with error '%s' (%d)\n"),
-			    strerror(errno),
-			    errno);
-	else
-		strbuf_addf(sys_info, "%s %s %s %s\n",
-			    uname_info.sysname,
-			    uname_info.release,
-			    uname_info.version,
-			    uname_info.machine);
+	get_uname_info(sys_info, 1);
 
 	strbuf_addstr(sys_info, _("compiler info: "));
 	get_compiler_info(sys_info);

connect.c

@@ -491,6 +491,9 @@ static void send_capabilities(int fd_out, struct packet_reader *reader)
 	if (server_supports_v2("agent"))
 		packet_write_fmt(fd_out, "agent=%s", git_user_agent_sanitized());
 
+	if (server_supports_v2("os-version") && advertise_os_version(the_repository))
+		packet_write_fmt(fd_out, "os-version=%s", os_version_sanitized());
+
 	if (server_feature_v2("object-format", &hash_name)) {
 		int hash_algo = hash_algo_by_name(hash_name);
 		if (hash_algo == GIT_HASH_UNKNOWN)

serve.c

@@ -29,6 +29,16 @@ static int agent_advertise(struct repository *r UNUSED,
 	return 1;
 }
 
+static int os_version_advertise(struct repository *r,
+			   struct strbuf *value)
+{
+	if (!advertise_os_version(r))
+		return 0;
+	if (value)
+		strbuf_addstr(value, os_version_sanitized());
+	return 1;
+}
+
 static int object_format_advertise(struct repository *r,
 				   struct strbuf *value)
 {
@@ -123,6 +133,10 @@ static struct protocol_capability capabilities[] = {
 		.name = "agent",
 		.advertise = agent_advertise,
 	},
+	{
+		.name = "os-version",
+		.advertise = os_version_advertise,
+	},
 	{
 		.name = "ls-refs",
 		.advertise = ls_refs_advertise,

t/t5555-http-smart-common.sh

@@ -123,9 +123,45 @@ test_expect_success 'git receive-pack --advertise-refs: v1' '
 '
 
 test_expect_success 'git upload-pack --advertise-refs: v2' '
+	printf "agent=FAKE" >agent_and_osversion &&
+	if test_have_prereq WINDOWS
+	then
+		git config transfer.advertiseOSVersion false
+	else
+		printf "\nos-version=%s\n" $(uname -s | test_redact_non_printables) >>agent_and_osversion
+	fi &&
+
+	cat >expect <<-EOF &&
+	version 2
+	$(cat agent_and_osversion)
+	ls-refs=unborn
+	fetch=shallow wait-for-done
+	server-option
+	object-format=$(test_oid algo)
+	0000
+	EOF
+
+	GIT_PROTOCOL=version=2 \
+	GIT_USER_AGENT=FAKE \
+	git upload-pack --advertise-refs . >out 2>err &&
+
+	test-tool pkt-line unpack <out >actual &&
+	test_must_be_empty err &&
+	test_cmp actual expect
+'
+
+test_expect_success 'git upload-pack --advertise-refs: v2 with osVersion.command config set' '
+	test_config osVersion.command "uname -srvm" &&
+	printf "agent=FAKE" >agent_and_long_osversion &&
+
+	if test_have_prereq !WINDOWS
+	then
+		printf "\nos-version=%s\n" $(uname -srvm | test_redact_non_printables) >>agent_and_long_osversion
+	fi &&
+
 	cat >expect <<-EOF &&
 	version 2
-	agent=FAKE
+	$(cat agent_and_long_osversion)
 	ls-refs=unborn
 	fetch=shallow wait-for-done
 	server-option

t/t5701-git-serve.sh

@@ -7,14 +7,17 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
 . ./test-lib.sh
 
-test_expect_success 'test capability advertisement' '
+test_expect_success 'setup to generate files with expected content' '
+	printf "agent=git/$(git version | cut -d" " -f3)" >agent_and_osversion &&
+
 	test_oid_cache <<-EOF &&
 	wrong_algo sha1:sha256
 	wrong_algo sha256:sha1
 	EOF
+
 	cat >expect.base <<-EOF &&
 	version 2
-	agent=git/$(git version | cut -d" " -f3)
+	$(cat agent_and_osversion)
 	ls-refs=unborn
 	fetch=shallow wait-for-done
 	server-option
@@ -23,7 +26,55 @@ test_expect_success 'test capability advertisement' '
 	cat >expect.trailer <<-EOF &&
 	0000
 	EOF
-	cat expect.base expect.trailer >expect &&
+
+	if test_have_prereq WINDOWS
+	then
+		git config transfer.advertiseOSVersion false
+	else
+		printf "\nos-version=%s\n" $(uname -s | test_redact_non_printables) >>agent_and_osversion
+	fi &&
+
+	cat >expect_osversion.base <<-EOF
+	version 2
+	$(cat agent_and_osversion)
+	ls-refs=unborn
+	fetch=shallow wait-for-done
+	server-option
+	object-format=$(test_oid algo)
+	EOF
+'
+
+test_expect_success 'test capability advertisement' '
+	cat expect_osversion.base expect.trailer >expect &&
+
+	GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \
+		--advertise-capabilities >out &&
+	test-tool pkt-line unpack <out >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'test capability advertisement with osVersion.command config set' '
+	test_config osVersion.command "uname -srvm" &&
+	printf "agent=git/$(git version | cut -d" " -f3)" >agent_and_long_osversion &&
+
+	if test_have_prereq !WINDOWS
+	then
+		printf "\nos-version=%s\n" $(uname -srvm | test_redact_non_printables) >>agent_and_long_osversion
+	fi &&
+
+	test_oid_cache <<-EOF &&
+	wrong_algo sha1:sha256
+	wrong_algo sha256:sha1
+	EOF
+	cat >expect_long.base <<-EOF &&
+	version 2
+	$(cat agent_and_long_osversion)
+	ls-refs=unborn
+	fetch=shallow wait-for-done
+	server-option
+	object-format=$(test_oid algo)
+	EOF
+	cat expect_long.base expect.trailer >expect &&
 
 	GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \
 		--advertise-capabilities >out &&
@@ -351,7 +402,7 @@ test_expect_success 'test capability advertisement with uploadpack.advertiseBund
 	cat >expect.extra <<-EOF &&
 	bundle-uri
 	EOF
-	cat expect.base \
+	cat expect_osversion.base \
 	    expect.extra \
 	    expect.trailer >expect &&
 

t/test-lib-functions.sh

@@ -2043,3 +2043,11 @@ test_trailing_hash () {
 		test-tool hexdump |
 		sed "s/ //g"
 }
+
+# Trim and replace each character with ascii code below 32 or above
+# 127 (included) using a dot '.' character.
+# Octal intervals \001-\040 and \177-\377
+# corresponds to decimal intervals 1-32 and 127-255
+test_redact_non_printables () {
+    tr -d "\n\r" | tr "[\001-\040][\177-\377]" "."
+}